package org.apache.lucene.search;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import org.apache.lucene.index.*;

final class ExactPhraseScorer extends PhraseScorer {

	ExactPhraseScorer(Weight weight, TermPositions[] tps, int[] offsets,
			Similarity similarity, byte[] norms) {
		super(weight, tps, offsets, similarity, norms);
	}

	protected final float phraseFreq() throws IOException {
		// sort list with pq
		pq.clear();
		for (PhrasePositions pp = first; pp != null; pp = pp.next) {
			pp.firstPosition();
			pq.put(pp); // build pq from list
		}
		pqToList(); // rebuild list from pq

		// for counting how many times the exact phrase is found in current
		// document,
		// just count how many times all PhrasePosition's have exactly the same
		// position.
		int freq = 0;
		do { // find position w/ all terms
			while (first.position < last.position) { // scan forward in first
				do {
					if (!first.nextPosition())
						return (float) freq;
				} while (first.position < last.position);
				firstToLast();
			}
			freq++; // all equal: a match
		} while (last.nextPosition());

		return (float) freq;
	}
}
